Method of producing a partial vacuum package



June 28, 1960 P. LERNER METHOD OF PRODUCING A PARTIAL VACUUM PACKAGE Filed Dec. 15, 1958 2 Shmat 1 VENTO PHILIP LERNER BY MM. 8 5

FIG. 4.

Aitmevs June 28, 1960 NE 2,942,390

METHOD OF PRODUCING A PARTIAL VACUUM PACKAGE Filed Dec. 15, 1958 2 Sheets-Sheet 2 FIG. 5.

FIG. 7.

INVENTOR. PH! Ll P LERNER United States Patent '0 1 2,942,390 METHOD OF PRODUCING A PARTIAL VACUUM PACKAGE Philip Lerner, 3818 N. 54th Blvd., Milwaukee, Wis.

' Filed Dec. 15,1958, Ser. No. 780,453

i Claims. (CI. 53-22 This, invention relates to a method ofproducing a partial vacuum and a product obtained thereby, and more particularly to a method of reducing the air pressure in a chamber without the need for complicated and expensive evacuating apparatus.

Heretofore, in the production of structure having a partially evacuated space, it has been the practice to seal the space and then withdraw some of the air from it by means, of vacuum pumps or the like. Or, the structure has been placed in a vacuum chamber and the air withdrawn, with the sealing step being subsequently performed.

.;The present invention is based on a novel concept which eliminates the need for complicated evacuation procedures, and contemplates moving a rigid or flexible member away from another inember to increase the air space. The invention is adaptedfor use in packaging food products and the like.

'Perishable food packages, such as those currently found in supermarkets, have been manufactured in a plurality of ways. In one method, the food product was placed on a support and a heat-shrinkable material placed therearound and sealed closed. The package was then subjected to heat, which shrunk the material toward and into tight engagement with the product. This method is disclosed in McCarty Patent No. 2,754,959.

In many instances it has been desired to provide a partial vacuum within the package, as where the food therein was perishable. This has required separate vacuum apparatus, as evidenced by Grinstead Patent No. 2,623,826.

The concept of the present invention provides a food product tightly enclosed by a shrinkable sealing film and partially vacuumized, without the need for evacuating apparatus. A separate evacuating step is eliminated.

' In addition, many prior tightly sealed food packages have been difiicult to open. The surrounding film has been engaged so tightly with the food product that the product was damaged when the film wascut into or broken. The package made by the method of the invention is easily openable without damage to the contents thereof. V

The accompanying drawings illustrate the best mode presently contemplated by the inventor for carrying out the invention. In the drawings:

Figure 1 is a vertical sectional view of a container showing the basic concept of the invention when applied thereto; i

Figure 2 is a perspective view of a package showing the initial positioning of the enclosing film;

Figure 3 is a view showing the shrinking step with the film in itsintermediat-e position;

Figure 4 is a vertical section of the package of Figure 2 after the shrinking step;

Figure 5 is-a vertical section of another form of package, with the film in its initial position;

Figure 6 is a view similar to Figure 5 after the shrinking step; and

Figure 7 is a vertical section of another food product formed ina similar manner. 1

Prior packaging lmethodsof the type discussed above film in tight contact with at least a portion of the food placed in a container 10 similar to container ,1.

2,942,390 Patented'June 28, 1960 have shrunk the enclosing film only for the purpose'oi tightening the film about the contents. in shrinking the film by heat or other means it was previously contemplated only to draw the film toward the package contents. Any air existing in the package was compressed if the package was previously sealed. If the space within the package was evacuated prior to the shrinking step, the latter increased the air pressure in the remaining space, which is not desirable. If shrinking was performed prior to evacuation and sealing, additional time was necessary to reduce the pressure to the desired value.

Figure 1 illustrates the concept of the invention which eliminates the evacuating step, while still providing a partial vacuum within the chamber. As shown in Fig. l, a circular cup-shaped receptacle or container 1 is provided with a fiat bottom 2 and vertical side wall 3. A

single piece of heat-shrinkable film-like material 4, such as vinylidene-chloride film, known by such trade names as Saran or Cryovac, is continuously joined to the upper edge of wall 3 by an annular seal 5, the seal being formed with heat or other suitable means.

Before seal 5 is made, film 4 is pressed inwardly and into somewhat loose engagement with the inner surfaces of bottom 2 and wall 3, as shown by dash lines 6. After therewithin. A partial vacuum has thus been created by' shrinking the film.

The depth of container 1 should be such as to provide a tight film surface across the top upon shrinkage.

Figures 2-4 show the method of the invention as applied to packaging. In Figure 2, a product 9 has been The relative sizes of product 9 andcontainer 10 are such that a substantial space 11 exists inwardly of the container walls, and with the latter extending above the product.- Once again, suitable heat shrinkable wrapping film ispressed downwardly into substantially contiguous contact with all exposed. surfaces of product 9 and container 10, as shown by dash lines 12. A continuous seal 13 is then made between the film and container edge.

The partially completed package is then placed in a closed heating chamber 14, having a source of heat such as burner 15 as shown in Fig. 3. Chamber 14 should he maintained at a suitable'temperature and for a period long enough to shrink the film to the final position shown at 16 in Fig. 4. Where the film is of a type which is relatively instantly shrinkable throughout its full extent when it reaches a certain temperature, the time necessary for complete shrinking may' be very short, i.e., a matter of only a few seconds. In Fig. 3, the film is shown as being disposed intermediate its initial and final positions. As can clearly be seen, the sealed space surrounding product 9 has been increased from substantially zero (Figure 2) to a relatively large volume (Figure 4), with a resultantsubstantial decrease in air pressure therein. The film was shrunk away from all surfaces withinthe package. v

If desired, the package may be submerged in hot water to shrink the film, or heated by any other suitable means.

Figures 5 and 6 show the application of the method to a food package wherein it is desired to havethe sealing as well as to have a partial vacuum.

As shown in Figure 5, a plurality of slices of meat or the like 17 are placed on a circular support 18 of cardboard, plastic or other suitable material. Support 18 is shown as being larger in diameter than meat 17, and comprises a relatively thin imperforate central disc portion '19, with relatively thin annular marginal flanges 20 and 21 extending outwardly from the respective upper and lower surfaces of the disc. Flanges 20 and 21 form a peripheral groove 22 therebetween.

After meat 17 is placed centrally on support 18, the usual heat shrinkable film 23 is placed thereover in substantially contiguous closely adjacent relationship and wrapped around beneath the support. In the wrapping process, care should be taken to position film 23 in engagement with the exposed top surface of flange 20. In addition, it is important to insert the film into groove 22 so that it is in substantially contiguous contact with the inner groove surfaces as shown in dash lines 24 in Fig. 5.

The wrapped film is then sealed to the bottom face of support 18 or to itself by a heating iron 25 or other suitable means. At this point there is very little air space within the sealed package.

The article is then placed in a heating chamber, similar to chamber 14, and when removed takes the configu ration shown in Figure 6. Film 23 shrinks during the heating step, and in so doing pulls out of groove 22' and away from the lower edge portion of meat 17, thus creating additional space in the package and a partial vacuum therewithin.

in some instances it may be desirable to utilize a support 18 which is just equal to or smaller in diameter than that of the food product. In this case, the method of the invention will operate in the same manner as above, except that the film will remain in contact with all exposed surfaces of the product, and will shrink away from the groove 22 only.

The heating step should be suflicient to stretch film 23 relatively tight across the edges of flanges 20 and 21. The taut condition of the film permits the package to be easily opened by inserting a sharp instrument, such as a knife 26, into groove 22 and passing it therearound. Upper flange 20 prevents the instrument from contacting and damaging the meat.

Once the package has been opened, support 18 may be removed and slices of meat 17 taken from what was originally the bottom of the stack of slices. The package may then be convenientlyre-wrapped by replacing support 18 in its original position and disposing the excess film, created by removing some meat, in groove 22 and then securing the film in the groove by string, a

rubber band, or the like.

In some instances it may be desirable to dispose a meat product on both sides of support 18. As shown in Fig. 7, a separate film may be disposed on each side of the support with the sheets meeting at the base of groove 22 and heat-sealed together at 27. Upon shrinking, the film will again draw out of the groove and tighten across the flange edges, as shown at 23.

Although the method and product of the invention.

have been described and shown with reference to round packages, it is contemplated-that both the product and, enclosing package can be of rectangular or other desired shape.

The method of the invention permits producing a partial vacuum by shrinking or moving one member away from another member. single step.

The food package produced by the method is partially vacuumized, and is easily opened without damage to the food contents.

Various modes of carrying out the invention are contemplated, as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

This is all' accomplished ina.

I claim:

1. A method of packaging a product in a partial vacuum, comprising the steps of placing the product on the bottom of a receptacle, disposing a shrinkable film closely adjacent said product and. the. inner walls of the receptacle, sealing said film along a continuous line to said receptacle and with said line being spaced from the bottom thereof, and shrinking said film away from said product and said walls to provide a sealed chamber having reduced air pressure surrounding the product.

2. A method of packaging a product in a partial vacuum, comprising the stepsof placing a product on the bottom of a receptacle with the product being spaced from at least a portion of the receptacle wall, disposing a heat shrinkable film closely adjacent said product and the inner wall of the receptacle with relatively little air space remaining therebetween, sealing said film along a continuous line to said receptacle and with said line being spaced from the bottom thereof, and heating said film to shrink the latter and cause it to draw away from said product and said wall to provide a sealed chamber having reduced air pressure surrounding the product.

3. A method of packaging a product in a partial vacuum, comprising the steps of placing the product on a support having a peripheral groove therein, disposing a shrinkable film closely adjacent said product and the inner surface of said groove, sealing said product from the outside air, and subsequently shrinking said film to draw the latter out of said groove and tighten the film onto at least a portion of the product.

4'. A method of packaging products in a partial vacuum, comprising the steps of placing products on each side of a support having a peripheral groove therein, dispos ing a shrinkable film closely adjacent each said product and the inner surfaces of said groove, sealing said products from the outside air, and subsequently shrinking said film to draw the latter out of said groove and tighten the film onto at least a portion of each product.

5. A method of packaging a product in a partial vacuum, comprising the' steps of placing the product on a disc having upper and lower marginal flanges extending outwardly therefrom to form a peripheral groove, placing a shrinkablefil-m over said prodnet and so that the film extends downwardly along the edge thereof and within said groove with the film being disposed closely adjacent said product and' the inner surfaces of said groove, sealing said film adjacent the lower side of. said disc, and subsequently shrinking said film to draw the latter out of said groove and partially away from said product to. form a sealed chamher having reduced air pressure therewithin, said film being shrunk tight between the edges of said flanges.

6. The method of claim 5 in which the said filmis of heat-shrinkable material, and the film is shrunk by the application of heat thereto. I

7. The method of. producing a partial vacuum in a package wrapped and sealed in a flexible shrinkable film material, comprising initially providing an air pocketin the package opening outwardly to the wrapping and disposing thewrapping in the pocket to displace the air therefrom at least partially, sealing the wrapping to prevent air entry to the package, and thereafter shrinking the wrapping to displace the same from said air pocket and thereby expand the air space within the package without admitting airthereto.

References Cited in the file of this patent UNITED STATES PATENTS 2,385,257 Cavallito Sept. 18, 1945 2,538,025 Moore Ian. 16, 1951 2,751,306 Snyder June 19, 1956 2,754,959 McCarty July 17, 1956 2,802,743 Ellies Aug. 13, 1957 .864.710 Pottle et al Dec. 16, 1958 WM M... 

